The present device relates broadly to the field of expansible chamber devices and more particularly to such devices utilizing reciprocating pistons.
The efficiency of conventional piston type expansion chamber devices is typically low. Energy is wasted in such devices in causing reciprocation of the piston, valving and in transmission of power developed (especially in internal combustion engines). Two and four cycle internal combustion reciprocating engines waste much energy for purposes of valving. Whether tappet or rotary valves are used, energy developed by the engine is sacrificed for their operation. In the typical internal combustion four cycle engine, a cam shaft is driven by the central power take-off crankshaft. Elongated push rods ride along the lobes of the cam and operate spring biased rocker arms. Valve stems are operated from the rocker arms. It is obvious that there is a considerable friction loss in such an arrangement. There is also difficulty in achieving and maintaining proper timing of these valve arrangements in relation to the reciprocation of the pistons.
More efficiency is realized with two cycle engines which often make use of rotary type valving or specially designed scavenging ports formed through the cylinder wall. These of course do away with much of the friction loss found with the more complex valving arrangements but also make sacrifices themselves in proper charging of the chambers and exhaust.
The necessary transmission of power from internal combustion engines and reciprocating piston pumps is another area of energy loss or inefficiency. Several connections are typically made through wrist pins, connecting rods, crankshafts, and finally to a power transmission. Friction is a considerable factor with such multiple connections.
A further problem with both pumps and reciprocating engines is bulk size and weight. An engine should be designed with high power output to weight. Conventional reciprocating piston engines do not make full use of their pistons and cylinders. This is especially true since only one side of the piston is typically used in engines having a single expandable chamber per cylinder. The weight is therefore considerable and has not to this time been effectively reduced. The size and weight of such devices create further difficulties in mounting and providing adequate space within their associated framework and carriage. Heavier members must be provided to support the engine or pump, therefore causing further weight disadvantages and waste of materials.
From the above problems it can be seen that it is desirable to obtain some form of expansible chamber device that will operate efficiently, producing an output that is high relative to its weight.